1. Field of the Invention
The present invention is broadly concerned with an improved web-fed printing press characterized by the provision of apparatus for rapid and easy changeover of press components between different press runs. More particularly, it is concerned with such a press, as well as the modular components thereof, which includes in the relevant press stations or towers improved apparatus for placement and removal of changeable press inserts as well as means for securely locking the inserts in place. In this fashion, presses in accordance with the invention can be changed over in a matter of minutes, while retaining the necessary high quality printing characteristics.
2. Description of the Prior Art
Printing press operators are often required to change over a press between press runs. For example, it may be necessary to change the diameter of offset tower cylinders to accommodate different printing requirements; and at the same time, bindery towers may also need to be changed to alter punching and perfing operations. Such changeover requirements are particularly acute for printers engaged in short runs, such as business forms printers who may typically have runs of only several thousand forms. In such cases, the changeover and make ready times may far exceed those of the actual printing runs themselves.
In response to these problems, it has been known in the past to provide convertible presses wherein the respective towers include a replaceable insert. In such presses, operators need only remove a structurally complete insert, typically comprising insert sidewalls supporting functional components such as offset cylinders, in order to change over a given station. In order to provide the most rapid and easy changeover operations, press owners normally stock a plurality of commonly used inserts, these being stored on a rack. A specially designed cart is also employed, which can be wheeled to the storage rack to receive an insert, whereupon it can be moved to the appropriate press station so that the insert can be shifted into operative position in the press.
While convertible presses of this character are known, problems remain in connection with the changeover operations. In particular, insert changeover with many convertible presses requires considerable exertion and effort on the part of the press operators, especially in final alignment and lockup of the inserts. Additionally, some prior convertible presses are deficient in that the insert locking apparatus is simply insufficient to precisely and rigidly align the inserts within the press stations. This can be a serious problem, because seemingly minor misalignment of a press insert within a station can lead to gross printing errors in the resulting run. It will further be appreciated that the conditions of vibrations and mechanical shock incident to press operation can also lead to insert misalignment and motion of the insert relative to the remainder of the station, even if the insert is initially aligned within the press station. Therefore, in order to be truly operable, a press insert must be readily alignable in the press station, and thereafter must be very securely locked in place to maintain alignment and prevent relative motion thereof.
Accordingly, there is a real unsatisfied need in the art for an improved convertible printing press apparatus providing ease of insert removal and placement, while at the same time giving precise, rigid lockup of the inserts during use.